1. Field of the Invention
The present invention relates to surgical instruments, and more particularly relates to a handle for an endoscopic or laparoscopic surgical instrument having a novel locking mechanism which is internally disposed within the handle to provide for incremental positioning of the jaw members of a surgical instrument in relation to each other. The positioning and subsequent release of the jaw members is accomplished through the provision of a trigger mechanism disposed within the handle.
2. Discussion of the Prior Art
In the prior art, various endoscopic surgical instruments are disclosed which utilize generally complex mechanisms for opening and closing handle members which actuate jaw members to facilitate use of the device at a surgical site. Many devices provide an intricate construction in which a linkage mechanism for opening and closing the jaws requires numerous moving parts, while a sliding arrangement is provided between two extended rod members to activate the linkage mechanism in response to movement of the handle members. In addition, pivoting of the handle members in many cases causes an unwanted radial torquing force on the rod which requires additional space to be provided in the handle members to accommodate the deflected radial movement of the rod.
Furthermore, it is often necessary for the surgeon, or an assistant, to maintain a constant force on the handles to keep the jaw mechanism closed in the event that the instrument is a grasping or gripping device such as forceps, needle holders, or retractors. This limits the surgeon's range, and in the case of an assistant, often requires additional personnel to be present in the operating room, thus restricting movement in an already confining location. To alleviate this problem, it has been known to provide locking mechanisms on the handles of the surgical instruments which allow the surgeon to lock or clamp the jaw members in place to free his hands to operate additional instruments during the course of the operation. Furthermore, this frees the surgical assistant to support the surgeon and eliminates the need for additional assistants. Typical locking devices include arm members which extend between the handles so that a series of ridges or ribs on each arm member engage corresponding ridges on the opposite arm to lock the handles in position. Bending one arm in relation to the other releases the locking mechanism.
A disadvantage associated with these devices concerns the release of the locking mechanism for subsequent movement of the jaw members to remove or reposition the instrument. Generally, the arm members of locking mechanisms are constructed of a resilient material, such as stainless steel or rigid plastic, and the locking forces which hold the arm members in engagement are generated by the natural flexing and biasing of the material of which the arm members are constructed. To release the locking mechanism, the arms must be disengaged by overcoming the locking forces of the arms. Typically, this is accomplished by manually flexing the arms away from each other, necessitating the use of two hands, one to grasp the instrument, and the other to forcibly move the arm members. This, of course, requires the surgeon (or assistant) to cease what he is doing and release the mechanism, thus reducing the effectiveness of the surgeon during the operation, particularly in an emergency situation.
Finally, locking mechanisms located on the handles require special care in sterilization, packaging and storage, as well as in normal handling in the operation room. Dirt and debris may clog the ribs of the locking mechanism thus reducing its effectiveness, and damage to the ribs during storage or packaging may destroy the ribs, rendering the locking mechanism useless.
U.S. Pat. No. 1,452,373, to Gomez discloses a typical locking mechanism for a surgical instrument, in which a plurality of ribs are provided on an extension of the handle member which engage a similar rib member on the opposite handle. Once engaged, the handles must be moved away from each other perpendicular to their longitudinal axis to disengage the locking mechanism to release the jaw mechanism.
U.S. Pat. No. 4,896,661, to Bogert et al. discloses a surgical instrument having a ratchet mechanism positioned on the handle members which includes a curved rack member attached to one handle member which passes through a slot in the other handle member. A releasable pawl member is provided on the second handle to engage the rack member and provide a means for releasing the ratchet.
U.S. Pat. No. 4,935,027, to Yoon discloses a surgical instrument having a ratchet mechanism positioned between the handle members. A rack member is provided which extends from one handle and passes through a slot in the second handle to lock the handles in place. Pivoting the rack member away from corresponding grooves in the slot will release the ratchet mechanism.
U.S. Pat. No. 4,428,374, to Auburn discloses a surgical instrument having means for positioning and holding the handle members in relation to each other. A rack member is provided on one handle member which extends through a slot in the second handle member in which a releasable pawl mechanism is provided to engage and disengage the rack member.
The novel surgical instrument pursuant to the present invention obviates the disadvantages encountered in the prior art and provides a precise instrument which is easy to manufacture and efficient to use, which eliminates the need for a external locking device and provides for one hand operation of the surgical instrument through manipulation of the opposing handles and a trigger mechanism. The instrument of the present invention incorporates many features which are of use to the surgeon during an operation, including a means for rotating the jaws in relation to the handle if desired, while maintaining a lightweight construction in an easy to handle device in which all of the features may be operated with one hand. Furthermore, the features are positioned so as to provide a maximum line of sight for the surgeon without obstructing the view to the surgical site.